Import Observed Data: Add option to control if curve names should be parsed to find a category

[magnesj]

In CVS import dialog, add option to control if the column name should be parsed and put into a category or use it as curve name. When the user wants to keep it as a curve name, put the curve in the Imported category.

• Make sure that calculations on these type of data is not distributed to other items.
• Make sure that observed data in this format is available as draggable item from Data Sources.